Apache Cassandra™ 1.2

Table statistics

Compaction metrics provide a number of statistics that are important for monitoring
performance trends.

For individual tables, ColumnFamilyStoreMBean provides the same general latency attributes as
StorageProxyMBean. Unlike StorageProxyMBean, ColumnFamilyStoreMBean has a number of other
statistics that are important to monitor for performance trends. The most important of these
are:

Compaction Metrics

Attribute

Description

MemtableDataSize

The total size consumed by this table's data (not including metadata).

MemtableColumnsCount

Returns the total number of columns present in the memtable (across all keys).

MemtableSwitchCount

How many times the memtable has been flushed out.

RecentReadLatencyMicros

The average read latency since the last call to this bean.

RecentWriterLatencyMicros

The average write latency since the last call to this bean.

LiveSSTableCount

The number of live SSTables for this table.

The recent read latency and write latency counters are important in making sure operations are
happening in a consistent manner. If these counters start to increase after a period of staying
flat, you probably need to add capacity to the cluster.

You can set a threshold and monitor LiveSSTableCount to ensure that the number of SSTables for a given table does not become too great.